Cell Relay Archive

[bannai@shell6.ba.best.com (Vinay Bannai)]

In article <6ejv3g$pf3$1@debris.uits.indiana.edu>,
Brian Lavallee <Brian.Lavallee.lauffen@nt.com> wrote:
>Hello all,
>
>Could someone please tell me why the industry is using AAL5 for MPEG-2
>transport instead of AAL2? Is it simply because AAL2 has not been
>standardized as quickly? Thanks!
>
>Regards,
>Brian

AAL5 SAR chips are plentiful and it is one of the most commonly used
adapatation layer currently used. Not to mention they are also cheap
compared to the other chips (I think). 

MPEG-2 needs the CDV and the jitter to be tightly controlled. Something
like AAL1 would be a good choice for it. But, MPEG-2 streams also carry
their own program reference clock which the MPEG-2 decoders recover thus
obivating the need to use AAL1. AAL1 also needs some sort of a common
network clock to function. This is a hard synchronization to provide.

Vinay

-- 
Vinay Bannai                     E-mail: bannai@best.com